The U.S. on Saturday pulled out of a U.N. agreement on migration and refugees, informing the governing body that it intends on deciding immigration policies for itself.

“Our decisions on immigration policies must always be made by Americans and Americans alone,” U.S. Ambassador to the U.N. Nikki Haley said. “We will decide how best to control our borders and who will be allowed to enter our country.”

The U.S. had signed on to the New York Declaration for Refugees and Migrants, adopted last September. The measure calls for a Global Compact on Migration to be developed in the near future, which would be “a significant opportunity to improve the governance on migration, to address the challenges associated with today’s migration, and to strengthen the contribution of migrants and migration to sustainable development,” according to the UN.

But Secretary of State Rex Tillerson claimed the decision to back out was due to concerns over U.S. sovereignty.

“While we will continue to engage on a number of fronts at the United Nations,” Tillerson said in a statement Sunday, “in this case, we simply cannot in good faith support a process that could undermine the sovereign right of the United States to enforce our immigration laws and secure our borders.”

The U.N. General Assembly president spoke out against the move, saying U.S. inclusion in the process is vital given its history.

“The role of the United States in this process is critical as it has historically and generously welcomed people from all across the globe and remains home to the largest number of international migrants in the world,” Miroslav Lajčák said in a statement.

“As such, it has the experience and expertise to help ensure that this process leads to a successful outcome.”